1. Field of the Invention
The present invention relates generally to a door latch device for a domestic electrical appliance, in particular a dishwasher. Particularly, the present invention relates to a door latch for a domestic electrical appliance comprising a frame provided or to be provided on a first component of the domestic appliance, a latching unit arranged so it can be displaced relative to the frame between an open position and a latched position for engagement with a closure system of a second component of the domestic appliance that can be moved relative to the first appliance component and is to be closed with respect thereto, and a latching spring assembly that pre-tensions the latching unit and which in the open position of the latching unit forces the unit into engagement with a blocking surface that blocks relaxation of the latching spring assembly.
2. Description of the Prior Art
Domestic electrical appliances for which the door latch device being considered here is suitable comprise a housing with a door opening which can be closed by a door that is movably hung on the appliance housing. The door latch device can be installed in the appliance housing or the door. In a preferred, although in no way limiting, embodiment the door latch device is fitted in the upper part of the appliance housing and engages downwards with a latching nose in a latching depression in the door.
A door latch device of the above-stated, generic type is known for example from US 2005/194795 A1. In this case the latching unit comprises a swivel part and a linearly movable slide that rotatably holds the swivel part about an axis of rotation. An arrangement of a plurality of pre-tensioning springs acts between the slide and a frame of the latching device. The force of the pre-tensioning springs forces the swivel part against an abutment secured to the frame. The circumferential contour of the swivel part has different radii, so, depending on the rotary position of the swivel part, the axis of rotation thereof is distanced from the abutment to a greater or lesser extent, and the pre-tensioning springs are tensioned more or less strongly accordingly.
The swivel part according to US 2005/194795 A1 comprises a gripping recess for a hook. In an unlocked rotary position, the gripping recess faces the hook so the hook can move into it as the door of the domestic appliance is being closed. In this rotary position, the swivel part is supported on the abutment with a part of its circumference which is located more radially outwards. The pre-tensioning springs are more strongly tensioned accordingly. If the hook moves into the gripping recess it presses against an edge thereof, and this introduces a rotation into the swivel part. In the process, with a sliding edge on which the edge portion of the swivel part which is located more radially outwards merges into an edge portion which is located more radially inwards, the rotary part moves past the abutment. This allows the pre-tensioning springs to relax, whereby the slide and the swivel part snap back in the direction of the abutment. At the same time the hook is locked in the gripping recess. It is only possible to turn back the swivel part if the slide and the swivel part are moved, against the force of the pre-tensioning springs, away from the abutment again, so the swivel part can be moved with its sliding edge in the opposite direction past the abutment again. This reverse movement of the swivel part is assisted by a restoring spring.